[Users] Programmatically changing the base map projection
Hugo
hfpmartins at gmail.com
Mon Jun 27 12:18:06 CEST 2011
Hello again,
Just to give some feedback on this. I've manged to correctly reproject the
map using the code suggestions that Matt pointed out. My problem was related
with the restrictedExtent of the base map that was bot being reprojected.
So, the only thing i've added to the code that Matt shared was the
following:
map.restrictedExtent = newBase.restrictedExtent;
After this, evryhting works fine.
Once again, thanks for pointing me in the right direction.
Cheers,
Hugo
On Fri, Jun 24, 2011 at 3:45 PM, Hugo <hfpmartins at gmail.com> wrote:
>
>
> Hi again,
>>>
>>> I think i've spoken to early. Matt, after digging a little bit more, your
>>> code suggestions are givinig me the same results as my initial approach. The
>>> strange thing is that, using your code and firbug, i see that the Center
>>> coordinates and bounding box for maxExtent are being correctly reprojected.
>>> Nevertheless, the map is going to a different place on earth (see attached
>>> images: mercator is ok but etrs is completely out).
>>
>>
> http://dl.dropbox.com/u/10817385/mercator.png
> http://dl.dropbox.com/u/10817385/etrs.png
>
>
>> No errors are shown in firebug and i'm a little bit lost. I have defined
>>> the etrs layer like the following:
>>>
>>> var ortos = new OpenLayers.Layer.TileCache(
>>> 'Ortofotomapas ARH',
>>> 'http://localhost/tilecache',
>>> 'Ortos',
>>> {
>>> isBaseLayer: true,
>>> maxExtent: bBoxEtrs,
>>> serverResolutions: mapResolutionsEtrs,
>>> visibility: false,
>>> transparent: true,
>>> scales: [800000, 500000, 250000, 100000, 50000, 25000, 10000,
>>> 5000, 2500, 1000],
>>> maxResolution:282.2220733500804,
>>> minResolution: 0.35277758727788067,
>>> units: 'm',
>>> projection: etrs,
>>> restrictedExtent: bBoxEtrs
>>> }
>>> );
>>>
>>> I'm sure that this tilecache layer is working properly because i've
>>> tested it on a simple openlayers app configured with the same options.
>>>
>>> Any hints on what might be happening??? Unfortunately, i can't see what
>>> is going wrong and have no more alternative ideas.
>>> Cheers,
>>>
>>> Hugo
>>>
>>>
>>>
>>> On Tue, Jun 21, 2011 at 2:42 PM, Hugo <hfpmartins at gmail.com> wrote:
>>>
>>>> Hi Matt,
>>>>
>>>> That works like a charm ;)
>>>> Really, thanks a lot for this suggestion and code!
>>>>
>>>> Cheers,
>>>>
>>>> Hugo
>>>>
>>>>
>>>>
>>>> On Mon, Jun 20, 2011 at 8:29 PM, Matt Priour <
>>>> mpriour at kestrelcomputer.com> wrote:
>>>>
>>>>> **
>>>>> I've had similar problems and I've solved it by adding an event
>>>>> listener to the map's baselayerchange event.
>>>>> you would put mapOptionsEtrs properties on the Etrs base layer rather
>>>>> than on the map. Map options are most ignored and overwritten by base layer
>>>>> options.
>>>>>
>>>>> here is my baselayerchange event handler, which is called with the map
>>>>> as scope.
>>>>>
>>>>> function onBaseLayerChange(evtObj){
>>>>> var mapProj, baseProj, map, newBase, reproject;
>>>>> map = this;
>>>>> newBase = evtObj.layer;
>>>>> mapProj = (map.projection && map.projection instanceof
>>>>> OpenLayers.Projection) ? map.projection : new
>>>>> OpenLayers.Projection(map.projection);
>>>>> baseProj = newBase.projection;
>>>>> reproject = !(baseProj.equals(mapProj));
>>>>> if (reproject) {
>>>>> var center, maxExt;
>>>>> //calc proper reporojected center
>>>>> center = map.getCenter().transform(mapProj, baseProj);
>>>>> //calc correct reprojected extents
>>>>> maxExt = newBase.maxExtent;
>>>>> //set map projection, extent, & center of map to proper values
>>>>> map.projection = baseProj;
>>>>> map.maxExtent = maxExt;
>>>>> map.setCenter(center);
>>>>> }
>>>>> }
>>>>>
>>>>> Matt Priour
>>>>> Kestrel Computer Consulting
>>>>>
>>>>> *From:* Hugo <hfpmartins at gmail.com>
>>>>> *Sent:* Monday, June 20, 2011 12:45 PM
>>>>> *To:* users at geoext.org
>>>>> *Subject:* [Users] Programmatically changing the base map projection
>>>>>
>>>>> Dear Geoext users,
>>>>>
>>>>> I'm trying to develop a functionality that will allow the user to
>>>>> change the base map projection. The initial map is using the spherical
>>>>> mercator projection so that OSM and Google/Yahoo/Bing layers can be
>>>>> displayed. Because the users will need to edit features at specific scales
>>>>> (1:25.000; 1:10.000) i need to develop a function that will change the
>>>>> projection from spherical mercator to ETRS PTM06 (EPSG:3763). I think i'm
>>>>> almost there but somehow, after reprojection the base map i get my map full
>>>>> extent much higher in latitude (so, more to the north) and much smaller in
>>>>> longitude (more to the west).
>>>>>
>>>>> My steps are:
>>>>> 1. Remove all OSM/Google/Yahoo/Bing layers from the map.
>>>>> 2. Add new options to the map
>>>>> 3. Merge new options (projection) to a blank layer and set it as
>>>>> basellayer
>>>>> 4. Loop the remaining layers and add new options.
>>>>>
>>>>> The relevant part of the code is below:
>>>>>
>>>>> //Map options
>>>>> var mapOptions = {
>>>>> maxExtent: bBox,
>>>>> maxResolution: 305.74811309814453,
>>>>> minResolution: 0.29858214169740677,
>>>>> resolutions: mapResolutions,
>>>>> units: 'm',
>>>>> projection: baseMercator,
>>>>> displayProjection: wgs,
>>>>> restrictedExtent: bBox,
>>>>> panMethod: OpenLayers.Easing.Quad.easeOut,
>>>>> numZoomLevels: 20,
>>>>> controls: []
>>>>> };
>>>>>
>>>>> var mapOptionsEtrs = {
>>>>> maxExtent: bBoxEtrs,
>>>>> maxResolution: 282.2220698223045,
>>>>> minResolution: 0.35277758727788067,
>>>>> resolutions: mapResolutionsEtrs,
>>>>> units: 'm',
>>>>> projection: etrs,
>>>>> displayProjection: etrs,
>>>>> restrictedExtent: bBoxEtrs,
>>>>> panMethod: OpenLayers.Easing.Quad.easeOut,
>>>>> numZoomLevels: 10,
>>>>> };
>>>>>
>>>>>
>>>>> //Reprojection logic
>>>>> var radioValue =
>>>>> Ext.getCmp('srsradiogroup').getValue().getGroupValue();
>>>>> var mapProj = map.getProjection();
>>>>> var baseCart = treePanel.getNodeById('basecartography');
>>>>> if (radioValue != mapProj && radioValue == 'EPSG:3763') {
>>>>> baseCart.cascade(function () {
>>>>> var childNodes = this.childNodes;
>>>>> for (i = 0; i < childNodes.length; i++) {
>>>>> switch (childNodes[i].text) {
>>>>> case 'OpenStreetMap':
>>>>> childNodes[i].disable();
>>>>> map.removeLayer(osm);
>>>>> break;
>>>>> case 'Google Streets':
>>>>> childNodes[i].disable();
>>>>> map.removeLayer(gstreets);
>>>>> break;
>>>>> // and so on...
>>>>> }
>>>>> }
>>>>> });
>>>>>
>>>>> map.setOptions(mapOptionsEtrs);
>>>>> map.layerContainerOrigin.transform(baseMercator, etrs);
>>>>>
>>>>> blankLayer.addOptions({
>>>>> projection: etrs
>>>>> });
>>>>> map.setBaseLayer(blankLayer);
>>>>>
>>>>> for (i = 0; i < mapPanel.map.layers.length; i++) {
>>>>> var className = mapPanel.map.layers[i].CLASS_NAME;
>>>>> if (className == 'OpenLayers.Layer.WMS') {
>>>>> mapPanel.map.layers[i].addOptions({
>>>>> srs: etrs
>>>>> });
>>>>> } else if (className == 'OpenLayers.Layer.Vector') {
>>>>> mapPanel.map.layers[i].projection = etrs;
>>>>> } else {
>>>>> //here i will control other types of layers like tilecache
>>>>> }
>>>>> }
>>>>> }
>>>>>
>>>>> Checking the map and layers projection through firebug, it seems
>>>>> everything is correct.
>>>>> I've also tried to get the initial extent of the map, reproject it and
>>>>> zoom to it after the reprojection but the it still goes to the same place.
>>>>>
>>>>> What might be the issues here?? Am i doing something completely wrong?
>>>>> Cheers,
>>>>>
>>>>> Hugo
>>>>>
>>>>>
>>>>>
>
>
> --
> Hugo Martins
> LabNT - ISEGI UNL
> Campus de Campolide
> 1070-312 Lisboa
> N 38°43'56.84", W 9°9'35.74"
>
--
Hugo Martins
LabNT - ISEGI UNL
Campus de Campolide
1070-312 Lisboa
N 38°43'56.84", W 9°9'35.74"
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